Optical discs are information recording media having a sector structure. Recently, the density and capacity of optical discs are becoming higher and higher. There is also an increasing demand for an improvement in physical characteristics of optical discs. In particular, if an optical disc has a limitation on the number of data rewrites in the same area, it is necessary to avoid repeated recording of data into a particular area of the optical disc. In order to avoid the repeated recording of data, a sequential recording method has been studied.
FIG. 14 is a diagram for explaining the principle of the sequential recording method.
In an example shown in FIG. 14, for the sake of simplicity, an information recording area on an optical disc is divided into 6 areas (A1 to A6). It is assumed that one hour of video data can be recorded in each of the 6 areas (A1 to A6) and the allowable number of rewrites on the optical disc (cycleability) is 1,000. For example, when 10-Mbps (Mega Bits/Second) video data is recorded onto a 27-GB (Giga Byte) optical disc, about 6 hours of video data can be recorded onto the optical disc.
A portion (a) of FIG. 14 shows a recording operation in which one hour of video data is repeatedly recorded into the area A1 1,000 times. A portion (b) of FIG. 14 shows a state of an optical disc that as a result of the recording operation of a portion (a) of FIG. 14, the area A1 is disabled due to rewrite fatigue attributed to physical characteristics of the optical disc. Since the area A1 is disabled, only 5 hours of video data can be recorded onto the optical disc which could otherwise store 6 hours of video data.
A portion (c) of FIG. 14 shows a sequential recording operation. In the sequential recording operation, video data is recorded in each area in order from the area A1 to the area A6; when the recording of video data reaches the end of the information recording area (i.e., the end of the area A6), the recording of video data returns to the start of the information recording area (i.e., the start of the area A1) and continues in order from the area A1 to the area A6.
A portion (d) of FIG. 14 shows a state of the optical disc that video data is rewritten into each of the area A1 to the area A6 167 times as a result of the sequential recording operation of the portion (c) of FIG. 14. Thus, the sequential recording operation averages the number of rewrites over the entire information recording area, thereby making it possible to reduce rewrite fatigue per area (e.g., per sector). As a result, even if one hour of video data is recorded 1,000 times, the time length of video data which can be recorded onto the optical disc is not reduced.
A data processing apparatus is known, in which an address indicating the starting position of a search for unallocated areas is recorded on an optical disc and an unallocated area (blank area) is searched for from the position indicated by the address in a direction from the inner area to the outer area of the optical disc (e.g., see Japanese Laid-Open Publication No. 4-120634).
However, in the case of applications in which a large volume of data, such as audio data or video data, is recorded, when rewrite is concentrated, such as repeated on the same area, a large area is no longer available. Therefore, there has been a demand for a recording method for avoiding the concentration of rewrites as maximally as possible. An information recording medium supporting defect management (e.g., a linear replacement method, etc.) has a problem that when the amount of disabled area is increased, a defect management list overflows, so that a defect management mechanism possessed by a recording apparatus (e.g., a drive, etc.) cannot work. Particularly, in the above-described conventional apparatuses, since data deletion is not taken into consideration, rewrite operations are likely to occur in data deleted areas. Further, since ECC blocks are not taken into consideration, rewrite operations disadvantageously occur in ECC blocks containing the end positions of data-recorded areas. Furthermore, since a specialized address indicating the starting position of a search for unallocated areas has to be recorded on an optical disc, a file system which does not have such a specialized address (e.g., an existing standard file system (e.g., UDF™ issued by OSTA, etc.) cannot handle the optical disc.
The present invention is provided to solve at least one of the above-described problems.